Synthetic resin-in-water emulsion, process for preparing same, and process for sizing cellulose therewith



United States Patent SYNTHETKC RESlN-lN-=WATER EMULEilUN, PROC- ESS FOR PREPARING SAME, AND PR 0CES FQR SIZING CELLULQSE THEREWITH Marion W. Picket], Eartiesville, @ida, assignor to Kerr- McGee Oil Industries, luc, a corporation of Delaware No Drawing. Filed Sept. 6, i957, Ser. No. 682,269

23 Claims. (Cl. Zed-29.6)

This invention relates to new and useful resin emulsions and to a new process for preparing such emulsions. More particularly this invention relates to resin-in-water type emulsions, the preferred dispersed phase being a synthetic resin.

The new synthetic resins exhibit many desirable properties and have been found to be particularly useful as ingredients in protective and decorative coating compositions, i.e. paints and polishes, and as sizing materials. While there is a large potential demand for acceptable emulsions of synthetic resins, their use in emulsion form has failed to gain 'wide acceptance due largely to the undesirable characteristics of emulsions produced by prior art processes. As examples of these undesirable characteristics, there may be mentioned, in general, low resistance to creaming sedimentation, breaking during handling, and poor dilution or letdown properties.

The prior art synthetic resin-in-water emulsions have further undesirable features when used for sizing paper or for Waterproofing cellulosic fibers. For example, if the emulsions are diluted or letdown they lose their ability to size paper or cellulosic fibers when stored for any appreciable length of time. A further undesirable feature is unless they have been set with a sizing aid such as paperinakers alum, the synthetic residue obtained on the paper or cellulosic fibers is readily water Wettable and unacceptable TAPPI values result. It will be apparent to those skilled in the art that it would be very advantageous, both from practical and economic viewpoints, to provide a synthetic resin emulsion and a process for effectively sizing paper or cellulosic fibers without the need for a costly sizing aid and without the necessity for the attendant close control of pH during the sizing process. Much time and effort has been spent by others in attempting to solve this and the foregoing problems, but without success prior to the present invention.

1 have discovered that if a synthetic polymeric olefin type resin is emulsified in water in the presence of an organic emulsifier which promotes the formation of oil-inwater type emulsions and by the process of the present invention, the resultant emulsion has very unusual and unique properties. The emulsions prepared in accordance with the present invention are unique in their ability to size paper or cellulosic fibers under either acidic or alkaline conditions and without the need for a sizing aid and exhibit phenomenal resistance to creaming, sedimentation, breaking during handling and may be readily diluted or letdown without adverse effect on the properties of the emulsion. The emulsions of the invention are further characterized by, among other things, a very small average particle size and exceptional uniformity of particle size.

It is an object of the present invention to provide new and improved resin-in-Water emulsions.

It is still a further object of the present invention to provide an improved resin-in-Water type emulsion of small average particle size, the preferred dispersed phase being synthetic resin.

It is still a further object of the present invention to provide an improved resin-in-water type emulsion of small average particle size, which is capable of sizing paper or cellulosic fibers to obtain improved Water resistant proper- Patented Sept. 25, 1962 ties even in the absence of a setting aid, and under both acidic and alkaline conditions.

It is still another object of the present invention to provide a new and improved process for producing the foregoing resin-in-water type emulsions.

It is still a further object of the present invention to provide a new and improved process for producing the foregoing resin-in-water type emulsions, the process being characterized by the presence of a small amount of an organic emulsifier of the type which promotes the formation of oil-in-Water type emulsions and continuously maintaining the phase volume ratio for the resin-water system during the emulsification process within the range yielding an emulsion having substantially a miximum viscosity at the temperature of emulsification.

These and other objects of the present invention will become more apparent to those skilled in the art by reference to the following detailed description.

The synthetic polymeric olefin type resins useful for the purpose of the present invention are derived by polymerizing one or more unsaturated materials such as ethylene, propylene, butylene, amylene, styrene, butadiene, and similar materials. The foregoing resins are available in commercial quantities and their preparation does not comprise a part of this invention. However, it may be stated that the preparation of these synthetic resins is particularly described in the text Organic Coating Technology, volume 1, pages 184-90, Henry Felming Payne, John Wiley & Sons, New York, N.Y.

The highly stable resin-in-water emulsions of the present invention are prepared with the aid of an organic emulsifying agent of the type promoting oil-in-water emulsions. The emulsions have an average resin particle size in the dispersed phase of less than 1 micron in diameter, preferably /2 to 1 micron in diameter or smaller with substantially no particles greater than 4 microns in diameter, providing the emulsification operation is carried out in accordance with the method to be described hereinafter. It will be appreciated that there are certain preferred procedural steps embodied in this method and that preferred emulsions are obtained when these preferred procedural steps are carried out. Otherwise, inferior emulsions are obtained.

It is an essential condition of the process of the invention that during emulsification the phase volume ratio for the resin-water system be maintained Within the range yielding an emulsion having substantially a maximum viscosity at the temperature of emulsification for the particular resin-water system. If this condition is not met, the average resin particle size in the dispersed phase of the emulsion will be greater than 1 micron in most instances.

The resin-in-water emulsions of the present invention are preferably prepared by a continuous method of controlled and simultaneous addition of the resin and water phases to achieve emulsification at the critical phase volume ratio which gives substantially a maximum viscosity at the temperature of emulsification. However, it is also possible to prepare the emulsions of the invention by a non-continuous process characterized by controlled separate and incremental addition of the resin and water phases to maintain the critical phase volume ratio existing in the preformed emulsion of the invention. Both methods maintain the phase volume ratio for the resinwater system within the range yielding an emulsion having substantially a maximum viscosity at the temperature of emulsification and thereby achieve control over particle size and certain other variables which have been considered heretofore to be a function of the emulsifying agent and speed of emulsification.

The continuous method mentioned above for producing emulsions of the present invention comprises incorporating the organic emulsifying agent in the water, preferably continuously, but it may also be added b-atchwise to the water. The water containing the organic emulsifier is then allowed to flow through a colloid mill at substantially less than half the mills capacity. A fluid synthetic resin is then fed to the colloid mill, the feed rate of synthetic resin being gradually increased as long as the viscosity of the emulsion produced is increasing. As the feed rate of fluid synthetic resin is being increased, at a certain synthetic resin to water ratio the emulsion viscosity will decrease in fact, if the feed rate of synthetic resin feed is to great the emulsion may even reverse. If the emulsion is reversed, the synthetic resin feed rate should be decreased or, alternatively, the feed rate of water containing the emulsifier may be increased until the synthetic resin to water ratio is such as to give a synthetic resin-in-water emulsion having substantially a maximum viscosity. The point where the emulsion viscosity no longer increases is the incipient reversal point and the emulsion will have substantially its maximum viscosity at this point for the particular temperature of emulsification. Once the feed rates of water and synthetic resin are adjusted to those proportions yielding substantially a maximum viscosity for the temperature of the emulsification, the feed rates are then maintained substantially constant to produce the emulsion of the present invention. However, it is understood that slight adjustments in the feed rates may be necessary from time to time.

If the rate of preparation of emulsion is too slow, the emulsion output may be increased by increasing the water feed rate and simultaneously increasing the fluid synthetic resin feed rate in quantities necessary to maintain the critical phase volume ratio, above discussed, which yields an emulsion of substantially a maximum viscosity for the emulsification temperature.

The off-grade emulsion made during start-up of operations, or at other times, which does not conform to the emulsion of the invention may be recycled to the colloid mill, thereby reducing the loss of raw materials. The recycling of emulsion is not limited to reclaiming of offgrade emulsion. For example, when it is desired to make emulsions using extremely low percentages of emulsifier, i.e. less than about 3% in the final emulsion, recycle of the emulsion is advantageous. Obviously, the preferred method of practicing this invention is to use sufficient emulsifier to produce a high grade emulsion without the necessity for recycling.

The emulsions of the present invention may also be produced by controlled separate and incremental addition of the two phases to obtain and maintain a critical phase volume ratio, if a colloid mill or similar equipment for continuous processing is not available. When using this embodiment of the present invention, a small amount of preformed emulsion is first prepared having substantially a maximum viscosity at the temperature of emulsification. This preformed emulsion is preferably formed by adding the fluid synthetic resin with agitation to a small amount of water containing up to 50% or higher of a suitable organic emulsifier. Usually the more emulsifier used the easier it is to obtain the desired preformed emulsion. The addition of fluid synthetic resin is continued as long as the viscosity of the emulsion increases. When a certain phase volume ratio of synthetic resin to water is exceeded the viscosity of the emulsion will decrease slightly and if addition of fluid synthetic resin is continued without further addition of water, the emulsion will invert to give a water-in-synthetic resin emulsion. Therefore, at the point where the viscosity of the emulsion first shows a decrease in value alternate incremental additions of water and fluid synthetic resin should be resorted to. The ratio of water to fluid synthetic resin which is added by the alternate incremental additions should be such as to maintain the phase volume ratio in those proportions where the first decrease in viscosity occurs.

The water added by alternate incremental addition may or may not contain emulsifier. The necessity for emulsifier in the water is determined by the amount of emulsifier present in the preformed emulsion, the percent emulsifier desired in the finished emulsion and the smallest amount of emulsifier necessary to effectively emulsify the synthetic resin. The smallest amount of emulsifier which will effectively emulsify synthetic resins in the present invention is approximately 0.5% by weight based on the total emulsion weight, but amounts up to 8% by weight, or higher may be used. The minimum amount of emulsifier is to a certain extent a function of the particular emulsifier being used and the particular resin being emulsified.

The physical characteristics of the synthetic resin materials useful in practicing the present invention may vary over a wide range. For example, the melting or softening points of suitable synthetic polymeric olefin type resins may vary from a melting or softening point too low to determine at room temperature to 350 F. or higher. The hardness of the synthetic resins may vary from s ft tacky substances to hard friable materials. The preferred synthetic resins usually have melting or softening points varying from F. to about 200 It has been found desirable when using synthetic resins having a melting or softening point of F. or greater to either cutback the synthetic resin with a suitable solvent for the purpose of obtaining a working fluidity at the desired temperature of emulsification, or otherwise resort to pressurized emulsification. The inclusion of solvent need in no way affect the ultimate use of the finished emulsion as the solvent may be of the volatile type and later volatilized during a drying operation incident to use of the emulsion. When the term synthetic resin is used in the specification and claims or when a specific synthetic resin is mentioned in the specification or claims, it is understood that if the softening point of the synthetic resin is too high for a proper working fluidity that either the synthetic resin has been cutback with a suitable solvent or pressurized emulsification is employed, or both.

Since many synthetic resins useful for the purpose of the invention have melting or softening points greater than 140 F., it is desirable to emulsify the synthetic resin-in-water at the highest practical temperature in order to prevent the synthetic resin from setting too fast. Temperature limitations are somewhat governed by the selection of a solvent used in cutting back the synthetic resins.

One reason for employing cutback synthetic resin is for ease of handling. When a synthetic resin is cutback with the solvent, its viscosity is lowered thereby facilitating its incorporation into the Water emulsion without the necessity of raising the temperature to the boiling point of water.

The ability of a given solvent to lower the viscosity of a particular synthetic resin over a temperature range is influenced to some degree by the viscosity characteristic with changing temperature exhibited by the given solvent. For example, a highly parafiinic solvent may give a smaller change in viscosity with temperature change than an aromatic type solvent. Therefore, the viscosity effect on the cutback synthetic resin at a particular temperature is a function of the percent synthetic resin and cutback solvent present in the mixture and their respective natures.

Among the many satisfactory volatile-type solvents that may be used are kerosene, gasoline, high-flash naphtha solvents, paraflinic raflinate type solvents, etc. Mineral spirits, an essentially non-aromatic material, is a preferred volatiletype solvent for synthetic resins which are paraffinic in nature since it possesses a high-flash point and a relatively narrow boiling range. The high-flash point of this solvent offers a safety feature and the boiling range of from approximately 300 to 400 F. permits relatively easy evaporation of the solvent when the emulsion of the present invention is used, if this is desirable.

When an aromatic-type solvent is used, the emulsions generally have satisfactory stability properties but give poorer TAPPI size values.

Among the many satisfactory non-volatile type solvent useful for the purposes of the invention are the normally non-volatile solvents such as either straight run or cracked heavy distillates. Specific examples of such solvents include fatty oils, recycle and gas oils, and lubricating stocks. Emulsions containing the non-volatile solvents are preferred in some instances, for example in the sizing of paper, where it is usually desirable for the non-volatile solvent to be retained as an integral part of the synthetic resin solids deposited on the paper.

The balance between the hydrophilic and hydrophobic groups of the emulsifier may be varied by changing the nature of the basic constituent which reacts with the acidic portion. For example, if potassium is substituted for sodium in the sodium soap of stearic acid, the potassium stearate thus formed is more amenable to the method of emulsification disclosed herein than is sodium stearate. This may be due to the better balance between the hydrophilic and hydrophobic groups of the emulsifying "agent, which has the eflect of permitting a greater variation in the synthetic resin to water phase volume ratio in the zone of emulsification near the incipient reversal point. With an emulsifying agent which may be referred to as having a proper balance between the hydrophilic and hydrophobic groups, it is relatively easy to adjust the synthetic resin to water phase volume ratio to maintain a substantially maximum viscosity near the incipient reversal point. With an emulsifying agent which has poor balance between the hydrophobic and hydrophilic groups, the phase volume ratio is so critical that the task of maintaining a substantially maximum viscosity near the incipient reversal point becomes extremely diflicult.

The maximum viscosity obtainable in accordance with the process of the invention varies with the temperature. For example when the emulsification occurs at a relatively low temperature, i.e. 120 F., the maximum viscosity is much higher than if the emulsification occurs at a higher temperature, i.e. 190 F, at least during the emulsification process and while the emulsion temperature is maintained at the higher temperature. However, if emulsions prepared at varying temperatures of emulsitication are allowed to cool to a given temperature, the viscosity of each will be approximately the same for any given synthetic resin-water system. The various organic emulsifiers may also have a tendency to affect the viscosity of the continuous phase (water) of the emulsion.

The organic emulsifiers useful for the purposes of the present invention are those known in the art as promoters of oil-in-water emulsions, such as water soluble soaps of fatty acids having a carbon chain within 14 to 18 carbon atoms, or mixtures of such fatty acid soaps. Examples of suitable fatty acids forming water soluble soaps include oleic, palmitic, stearic, lauric, naphthenic, oxidized hydrocarbons containing carboxylic groups, tall oil, rosin acid (primarily abietic acid or its derivatives) and mixtures thereof. The water soluble alkali metal soaps of rosin and tall oil are preferred for economic reasons.

The water soluble organic salt type emulsifiers useful in the practice of this invention may be prepared by reacting fatty acids with a basic substance including alkali and lower organic amines having less than 6 carbon atoms in the chain. Examples of suitable organic amines include ethanol amine, morpholine and ethylamine. Examples of suitable alkali include the alkali oxides, hydroxides, and carbonates, of which sodium hydroxide is usually preferred. This preference is primarily of an economic nature and in certain instances potassium hydroxide is preferred, as above referred to in the case of stearic acid soaps. When ammonium soaps are used, an excess of free ammonia or ammonium hydroxide is 6 normally used because of the pronounced tendency of ammonia to be volatilized during the emulsification process.

Other suitable emulsifying agents for the purpose of the present invention are the alkali salts or soaps of organic sulfonic acids which are known to be promoters of oil-in-water emulsions. Examples of such emulsifying agents are the alkali salts or soaps of alkyl sulfonic acid, aryl sulfonic acid and alkyl aryl sulfonic acid. The alkyl aryl sulfonates are available commercially as sodium octydecyl benzene sulfonate and Nacconal NR, a sodium alkylaryl su-lfonate made from kerosene and marketed by National Aniline .and Dye Corporation.

While formulations for the emulsion according to the present invention may vary somewhat and depend to some extent upon the characteristics of the various individual ingredients, a preferred formulation for preferred synthetic resin-inwater emulsions is as follows:

Percent Synthetic resin 40-60 Solvent (cutback) 0-20 Emulsifying agent 0.5-8 Water (approximately) 30-40 The above formulation is not intended to preclude the use of higher percentages of emulsifying agent or of solvent. As much as 20% by Weight and higher of emulsifier will usually for-m satisfactory emulsions. Higher percentages by weight of solvents may also be desirable if the synthetic resin is of an extremely viscous nature. For example, when emulsifying synthetic resins having a melting or softening point of about 300 F. or higher, it is generally preferred to use a formulation comprising 30 to 50% solvent, and in some cases up to solvent, in order to reduce the extremely high viscosity. In such instances, it is understood that the percentage of water will depend upon the quantity of water necessary to form an emulsion haying substantially a maximum viscosity for the particular resin-water system at the temperature of emulsification.

Examples of the preparation and use of typical emulsions in accordance with the process of the invention are as follows:

EXAMPLE I A chemicollcid pilot plant colloid mill driven by a 1 hp., 3600 r.p.m., 220 volt, 3 phase motor was used in the production of an emulsion by the preferred continuous once through emulsification process of the present invention.

To start the emulsification, a water solution containing 20% by weight of sodium tallate was fed to the mill at the rate of about 20 lbs. per hour. Then fluid Piccopalea commercial synthetic polymer of 212 F. soften ing point which is essentially linear or parafiinic in nature and derived by polymerizing an unsaturated petroleum gaswas fed to the mill. The rate of feed of synthetic resin was initially low and gradually increased. It was found desirable to cutback the synthetic resin with mineral spirits at the rate of 66 parts by weight of mineral spirits to 200 parts by weight of the resin.

The soapy water and fluid synthetic resin was injected into a common line substantially at the point where the line entered the colloid mill. The emulsion coming from the mill at this time was very fluid due to the low initial feed rate of synthetic resin, L6. to the low phase volume ratio. The feed rate of fluid synthetic resin was increased to thereby change the phase volume ratio of synthetic resin to water. This had the effect of increasing the viscosity of the emulsion, and the feed rate of synthetic resin was continually increased as long as the viscosity of the emulsion from the mill increased. Eventually .a point was reached where an increase in the feed rate of synthetic resin began to cause a decrease in the viscosity of the emulsion. This indicated an incipient reversal of phases or perhaps in some cases complete reversal of phases. At this point, the feed rate of synthetic resin was decreased until the phase volume ratio was approximately the same as the phase volume ratio where the initial drop in viscosity of the emulsion occurred. The water feed rate also may be increased to achieve the same objective. Minor adjustments of the feed rates of synthetic resin and water were than made as needed to give an emulsion of substantially a maximum viscosity at the temperature of the emulsification. It was also possible to start the foregoing continuous emulsification process by starting the synthetic resin feed first and then increasing the soapy water feed rate until a point was reached whereby the emulsion had a maximum viscosity.

By the above process, emulsions were produced having substantially a maximum viscosity for the temperature of emulsification. The particles in the dispersed phase of the emulsion were exceptionally uniform, exhibiting an average particle size of less than /2 micron in diameter, very few particles of a larger size, and substantially no particles of a diameter greater than 4 microns. The preferred emulsion thus produced was found to contain about 200 parts by weight synthetic resin, 66 parts by weight mineral spirits, 1 part by weight soap to each 10 parts by weight of synthetic resin, in addition to sufficient water to produce an emulsion having substantially a maximum viscosity at the temperature of emulsification.

The foregoing process may be modified so as to recycle at least a portion of the emulsion. This modification is desirable in reclaiming the offgrade emulsion produced in starting the emulsification process, and also will allow more convenient operation when less than about 5% emulsifier is used.

The above procedure may be modified by operating the colloid mill under pressure if it is undesirable to incorporate a solvent in the emulsion formulation. A suitable pressure is usually about 100 pounds p.s.i., but higher pressures may be necessary if the melting or softening point of the synthetic resin is unusually high. This allows the synthetic resin to be heated to temperatures such that it possesses the proper fluidity characteristics and yet will not permit boiling of the water phase in the colloid mill. In such a pressurized system, it is necessary to allow the finished emulsion to cool under pressure to a temperature well below the boiling point of water, preferably to a temperature as low as 140 F. In pressurized systems, the viscosity of the emulsion may be controlled by installing a viscosimeter of the Ultra-Viscoson type in the flow line leading from the colloid mill to the pressurized reservoir.

EXAMPLE II A coumarone-indene resin-in-Water emulsion was prepared by the preferred continuous once through emulsification process described in Example I. The formulation of this emulsion was identical with that of Example I, with the exception of substituting an aromatic polymeric olefin type resin for the paraffinic type resin of Example I. The substituted resin was made by polymerization of coumarone and indene to give a resin polymer having a softening point of 220 F. Thus the formulation consisted of 200 parts by weight coumarone-indene polymeric resin, 66 parts by weight mineral spirits, 1 part by weight sodium tallate to each parts by weight of polymeric resin, together with sutficient water to produce an emulsion having a maximum viscosity at the temperature of emulsification.

The above emulsion was found to have an average particle size of 2 microns and exhibited particles of a larger size, but substantially no particles of a size greater than 4 microns. It will be observed from data appearing hereinafter that this emulsion performed poorly as a paper size as compared with the emulsion of Example I.

EXAMPLE III A second coumarone-indene resin-in-water emulsion was prepared by the preferred continuous once through emulsification process of Example I. The formulation for this emulsion differed from that of Example II in that the mineral spirits solvent was replaced with a highly aromatic solvent. Thus, the formulation of the emulsion consisted of 200 parts by weight courmarone-indene polymeric resin having a softening point of about 200 F., 66 parts by Weight aromatic solvent, 1 part by Weight sodium tallate to each 10 parts by Weight resin, together with sufficient water to produce an emulsion having a maximum viscosity for the temperature of emulsification.

The above emulsion was found to have an average particle size of 1 micron and very few particles larger than 1 micron in diameter. This emulsion gave rather indifferent TAPPI size values on both the acid and alkaline side with or without a fixative, such as alum, but when a highly parafiinic solvent was used to cutback the highly aromatic resin, the resulting emulsion gave improved TAPPI size values on both the alkaline and acid side with and without the use of a fixative. This difference in sizing values may be attributable to a better paraffinic-arornatic balance in the emulsion.

EXAMPLE IV The emulsions prepared in Examples I and II were used to size paper at the 2% size level giving results as shown below in Table I:

Douglas Fir Kraft Pulp The data in the above table illustrates that the preferred emulsions of the present invention will size paper on both the alkaline and acid sides. The use of alum or close control of pH is not necessary in setting the size.

The table further illustrates the unique and unusual properties of preferred emulsions prepared in accordance with the process of the present invention, the prepared emulsions being characterized by an average particle size of less than 1 micron in diameter and very few particles of a larger size. Thus the emulsion of Example I, which had an average particle size of less than /2 micron in diameter, is superior as a sizing agent for paper than the emulsion of Example II, which had an average particle size of 2 microns. The emulsions prepared from synthetic resins which are essentially linear polymers or paraffinic in nature are preferred for use in the sizing of paper. If it is desired to use synthetic resins of a cyclic nature, such as coumarone-indene resin, it is usually desirable to form the emulsion using an aromatic solvent to thereby obtain an emulsion which sizes paper stock better on the alkaline and acid side with or without a fixative such as alum.

EXAMPLE V Example I describes the preferred continuous once through emulsification process of the invention. However, it is also possible to form the emulsion of the present invention by a batch process as described below. The emulsion formulation was identical with that of Example I.

1 part by weight of sodium tallate for each 10 parts by weight of Piccopale resin was placed in a vessel with approximately an equal quantity by weight of water. The fluid Piccopale resin was cutback with mineral spirits and maintained at a temperature of about 300 F., then gradually added to the water solution of sodium tallate with vigorous agitation. A mixer capable of developing high torque at low speed and so designed as to sweep the entire mixing area of the vessel, which may be of the conventional bakery mixer type was used in agitating the mixture. The viscosity was found to gradually in crease upon slow addition of the piccopale resin. Upon continued addition of the resin, the viscosity reached a maximum and then showed a tendency to decrease indicating a tendency toward incipient reversal of the mixture to form a water-in-resin emulsion. It is this emulsion which contains a fractional portion of the total resin to be emulsified and which is at substantially a maximum viscosity for the synthetic resin-water system at the temperature of emulsification that is referred to in the specification and claims as being a preformed emulsion. At this point, it is necessary to begin the incremental addition of water, preferably at ambient temperature. The controlled addition of water prevents undesirable reversal of the emulsion and maintains the viscosity of the emulsion at substantially a maximum for the temperature of the emulsification. Maintaining the mixture at substantially the maximum viscosity of the emulsion at its temperature of emulsification is essential to produce the fine particle size of the emulsion of the instant invention.

Increments of water may now be added alternately with increments of the resin, or simultaneously, thus maintaining the critical phase volume ratio which gives the necessary high viscosity. The incremental addition of water and synthetic resin is continued until all the resin has been incorporated in the mixture and the emulsification is completed. The emulsion thus prepared was found to have an average particle size of less than /2 micron in diameter and very few particles of a larger size. The characteristics and properties of an emulsion prepared by a batch process are substantially the same as the emulsions prepared by the continuous process of Example 1. During the batch preparation of the emulsions, the temperature will usually be within the range of l20130 F. An outside source of heat is not necessary during the preparation of the emulsion since the synthetic resin-solvent mixture is added at a temperature up to about 300 F.

When a poly propylene polymer or a polyethylene polymer of medium melting range was substituted for the Piccopale resin of Example I, e.g. Epolene N (a proprietary product of Eastman Chemical Company), the resulting emulsions had similar properties and gave satisfactory paper size values.

EXAMPLE VI A Piccopale resin-in-Water emulsion was prepared by the preferred continuous once-through emulsification process described in Example I. The procedure followed and the formulation of this emulsion was identical with that of Example I, with the exception of substituting Nacconol NR for the sodium tallate emulsification agent of Example I. Thus, the formulation consisted of 200 parts by weight of Piccopale resin, 66 parts by weight of mineral spirits, and 1 part by weight of Nacconol NR for each parts by weight of Piccopale resin, together with sufficient water to produce an emulsion having a maximum viscosity at the temperature of emulsification.

The above prepared emulsion was found to have an average particle size of less than /2 micron in diameter, very few particles of a larger size, and substantially no particles of a diameter greater than 4 microns. When used to size paper at the 2% size level, the results were substantially the same as given in Example IV for the emulsion of Example 1.

Once an emulsion of the present invention has been prepared, whether by the batch or continuous process, the unusual and unique properties of the emulsions are not adversely affected by further additions of water. For example, the emulsions of the present invention, after the emulsification is completed, may be diluted or letdown to meet the specifications of customers requirements for an emulsion of lower solid content. The emulsions of the present invention, whether in a concentrated or let- 1% down form exhibit phenomenal resistance to creaming, sedimentation, resistance to breaking during handling in pumps, etc., and may be stored for relatively long periods of time without adverse effect.

The foregoing specific description of the present invention is for the purpose of illustration only and is not limiting to the scope of the invention which is set forth in the claims.

I claim:

1. A synthetic resin-in-water emulsion having as an emulsifying agent a water soluble organic emulsifier which promotes the formation of oil-in-water type emulsions, an average particle size in the dispersed phase of less than 1 micron in diameter with substantially no particles in the dispersed phase of a diameter greater than 4 microns and the emulsion being prepared by a process comprising emulsifying at least one synthetic resin selected from the group consisting of polymers of polymerizable ethylenical- 1y unsaturated monomers and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith and water in the presence of an organic emulsifying agent selected from the group consisting of Water soluble nonsulfo, detergent-forming, carboxy acid soaps and water soluble soaps of organic sulfonic acids by dispersing the synthetic resin in the water in a ratio providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification.

2. The synthetic resin-in-water emulsion of claim 1 wherein the synthetic resin is parafiinic in nature.

3. The synthetic resin-in-water emulsion of claim 1 wherein at least a portion of the synthetic resin structure is cyclic in nature.

4. The synthetic resin-in-water emulsion of claim 1 wherein the synthetic resin is a coumarone-indene resin.

5. The synthetic resin-in-water emulsion of claim 1 wherein the emulsifier is a water soluble soap of a higher fatty acid.

6. The synthetic resin-in-water emulsion of claim 1 wherein the emulsifier is an alkali salt of an organic sulfonic acid.

7. In a process for preparing a synthetic resin-in-water emulsion having as an emulsifying agent an organic emulsifier which promotes the formation of oil-in-water emulsions selected from the group consisting of water soluble non-sulfo, detergent-forming, carboxy acid soaps and water soluble soaps of organic sulfonic acids, the improvement which comprises emulsifying at least one synthetic resin selected from the group consisting of polymers of p-olymerizable ethylenically unsaturated monomers and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith and water in the presence of the emulsifying agent by dispersing throughout the emulsification the synthetic resin in the water in a ratio of synthetic resin to water providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification, the synthetic resin being in the liquid phase at the time of emulsification, the resultant synthetic resin-inwater emulsion having an average particle size in the dispersed phase of less than one micron in diameter and substantially no particles in the dispersed phase of a diameter greater than four microns.

8. In a process for preparing a synthetic resin-in-water emulsion having as an emulsifying agent an organic emulsifier which promotes the formation of oil-in-Water emulsions selected from the group consisting of water soluble, non-sulfo, detergent-forming, carboxy acid soaps and water soluble soaps of organic sulfonic acids, the improvement which comprises producing a preformed emulsion which constitutes a minor portion of the total emulsion by emulsifying a minor portion of the constituents of the emulsion, the preformed emulsion being prepared by emulsifying at least one synthetic resin selected from the group consisting of polymers of polymerizable ethylenically unsaturated monomers and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith and water in the presence of the emulsifying agent by dispersing throughout the emulsification the synthetic resin in the water in a ratio of synthetic resin to water providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification, and then preparing an additional portion of the emulsion while continuously maintaining the phase volume ratio of the synthetic resin and water within the range yielding substantially a maximum viscosity for the synthetic resin-in-water system at the temperature of emulsificati'on, the additional portion of the emulsion being prepared by dispersing throughout the emulsification the synthetic resin in the water in a ratio of synthetic resin to water providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification, the synthetic resin being in the liquid phase at the time of emulsification, the resultant synthetic resin-in-water emulsion having an average particle size in the dispersed phase of less than one micron in diameter and substantially no particles in the dispersed phase of a diameter greater than four microns.

9. The process for forming the synthetic resin-in-water emulsion of claim 8 wherein the synthetic resin is paraffinic in nature.

10. The process for forming the synthetic resin-in-water emulsion of claim 8 wherein at least a portion of the synthetic resin structure is cyclic in nature.

11. The process for forming the synthetic resin-inwater emulsion of claim 8 wherein the synthetic resin is coumarone-indene resin.

12. The process for forming the synthetic resin-inwater emulsion of claim 8 wherein the emulsifier is a water soluble sOap of a higher fatty acid.

13. The process for forming the synthetic resin-in-water emulsion of claim 8 wherein the emulsifier is an alkali salt of an organic sulfonic acid.

14. In a process for preparing a synthetic resin-in-water emulsion having as an emulsifying agent an organic emulsifier which promotes the formation of oil-in-Water emul sions selected from the group consisting of water soluble, non-sulfo, detergent-forming, monocarboxy acid soaps and water soluble soaps of organic sulfonic acids, the emulsion having an average particle size in the dispersed phase of less than one micron in diameter and substantially no particles in the dispersed phase of a diameter greater than four microns and being prepared from at least one synthetic resin selected from the group consisting of polymers of polymerizable ethylenically unsaturated monomers and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith, which comprises producing a preformed emulsion which constitutes a portion of the total emulsion by emulsifying minor portions of the constituents of the emulsion, the preformed emulsion being prepared by emulsifying the synthetic resin and water in the presence of the emulsifying agent by dispersing the synthetic resin in the water in a ratio providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification, creating a stream of the preformed emulsion, continuously introducing synthetic resin and water into the stream of preformed emulsion at a rate to continuously maintain the phase volume ratio of the synthetic resin-water system within the range yielding substantially a maximum viscosity for the system at its temperature, efiecting turbulence in the stream, applying emulsifying agent to the stream of preformed emulsion prior to effecting turbulence, the synthetic resin being in the liquid phase at the time of emulsification, con- 12 tinuously withdrawing a portion of the emulsion stream subsequent to effecting turbulence and circulating the remainder of the emulsion stream as fresh preformed emulsion stream.

15. The process for forming the synthetic resin-in-water emulsion of claim 14 wherein the synthetic resin is paraffinic in nature.

16. The process for forming the synthetic resin-in-water emulsion of claim 14 wherein at least a portion of the synthetic resin structure is cyclic in nature.

17. The process for forming the synthetic resin-in-water emulsion of claim 14 wherein the synthetic resin is coumarone-indene resin.

18. The process for forming the synthetic resin-in-water emulsion of claim 14 wherein the emulsifier is a water soluble soap of a higher fatty acid.

19. The process for forming the synthetic resin-in-water emulsion of claim 14 wherein the emulsifier is an alkali salt of an organic sulfonic acid.

20. The process for sizing a cellulosic product of a fibrous nature which comprises the'steps of depositing on the fibers of the cellulose active sizing constituents of a resin-in-water emulsion by intimately contacting the cellulosic fibers with the emulsion in the absence of a precipitating agent; the dispersed phase of the emulsion consisting essentially of synthetic resin selected from the group consisting of polymers of an ethylenically unsaturated monomer and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith; the emulsion being characterized by having as an emulsifying agent an organic emulsifier which promotes the formation of oil-in-water emulsions selected from the group consisting of water soluble, non-sulfo, detergentforming, carboxy acid soaps and water soluble soaps of organic sulfonic acids, an average synthetic resin particle size in the dispersed phase of less than one micron in diameter with substantially no particles in the dispersed phase of a diameter greater than four microns, an ability to size the cellulosic fibers on the acid side and the alkaline side and in the absence of a precipitating agent, and the emulsion being produced by emulsifying the synthetic resin and Water in the presence of the emulsifying agent by dispersing the synthetic resin in the water in a ratio providing an emulsion having substantially the maximum viscosity for the synthetic resin-in-water system at the temperature of emulsification; and subsequently forming the resultant sized fibers into manufactured form.

21. The process of claim 20 wherein the cellulosic fibers are sized at a pH above 7.0.

22. The process of claim 20 wherein the cellulosic fibers are sized on the acid side.

23. A process for preparing a sized cellulosic product of a fibrous nature from unsized cellulose fibers and synthetic resin which comprises the steps of first preparing from synthetic resin selected from the group consisting of polymers of a polymerizable ethylenically unsaturated monomer and inter-polymers of an ethylenically unsaturated monomer and at least one different ethylenically unsaturated monomer inter-polymerizable therewith and water a synthetic resin-in-water emulsion having as an emulsifying agent a water soluble organic emulsifier which promotes the formation of oil-in-water type emulsions selected from the group consisting of water soluble, nonsulfo, detergent-forming, carboxy acid soaps and water soluble soaps of organic sulfonic acids, the emulsion having an average particle size in the dispersed phase of less than 1 micron in diameter with substantially no particles in the dispersed phase of a diameter greater than 4 microns, the emulsion being prepared by a process including producing a preformed emulsion which constitutes a small fractional portion of the total emulsion by emulsifying minor proportions of the constituents of the emulsion to obtain a viscosity of substantially the maximum obtainable for the synthetic resin-water system at the temperature of emulsification, creating a stream of at least a portion of the preformed emulsion, continuously introducing synthetic resin and Water into the stream of preformed emulsion at a rate to continuously maintain the phase volume ratio of the synthetic resin-water system within the range yielding substantially a maximum viscosity for the system at its temperature, effecting turbulence in the stream, supplying emulsifying agent to the stream of preformed emulsion prior to effecting turbulence, continuously withdrawing a portion of the stream subsequent to turbulence and circulating the remainder as fresh preformed emulsion stream, the withdrawn emulsion having an ability to size the cellulosic fibers on the acid side and the alkaline side and in the absence of a precipitating agent, thereafter depositing on the fibers of cellulose active sizing constituents of the withdrawn resinin-water emulsion by intimately contacting the cellulosic fibers with the emulsion in the absence of a precipitating agent, and subsequently forming the resultant sized fibers into manufactured form.

14 References Qited in the file of this patent UNITED STATES PATENTS 1,976,433 Ceetham Oct. 9, 1934 2,051,410 Keny Aug. 18, 1936 2,069,178 Dent Jan. 26, 1937 2,238,956 Strother Apr. 22, 1941 2,373,347 Schoenfelcl Apr. 10, 1945 2,388,600 Collins Nov. 6, 1945 2,398,344 Collins et al. Apr. 16, 1946 2,635,086 Norris Apr, 14, 1953 2,653,919 Hunter Sept. 29, 1953 2,731,433 Johnson Jan. 17, 1956 2,766,214 Erchak et al. Oct. 9, 1956 OTHER REFERENCES Casey: Pulp and Paper, volume 1, Interscience Pub. Inc., New York (1952), pages 522-4, 540.

Bennett: Practical Emulsions (1943), Chemical Publishing Co., Inc. Brooklyn, New York, pages 37, 38 and 

1. A SYNTHETIC RESIN-IN-WATER EMULSION HAVING AS AN EMULSIFYING AGENT A WATE SOLUBLE ORGANIC EMULSIFIER WHICH PROMOTES THE FORMATION OF OIL-IN-WATER TYPE EMULSIONS, AN AVERAGE PARTICLE SIZE IN THE DISPERSED PHASE OF LESS THAN 1 MICRON IN DIAMETER WITH SUBSTANTIALLY NO PARATICLES IN THE DISPERSED PHASE OF A DIAMETER GREATER THAN 4 MICRONS AND THE EMULSION BEING PREPARED BY A PROCESS COMPRISING EMULSIFYING AT LEAST ONE SYNTHETIC RESIN SELECTED FROM THE GROUP CONSISTING OF POLYMERS OF POLYMERIZABLE ETHYLENTICALLY UNSATURATED MONOMERS AND INTER-POLYMERS OF AN ETHYLENICALLY UNSATURATED MONOMER AND AT LEAST ONE DIFFERENT ETHYLENICALLY UNSATURATAED MONOMER INTER-POLYMERIZABLE THEREWITH AND WATER IN THE PRESENCE OF AN ORGANIC EMULSIFYING AGENT SELECTED FROM THE GROUP CONSISTING OF WATER SOLUBLE NONSULFO, DETERGENT-FORMING, CARBOXY ACID SOAPS AND WATER SULUBLE SOAPS OF ORGANIC SULFONIC ACIDS BY DISPERSING THE SYNTHETIC RESIN IN THE WATER IN A RATIO PROVIDING AN EMULSION HAVING SUBSTANTIALLY THE MAXIMUM VISCOSITY FOR THE SYNTHETIC RESIN-IN-WATER SYSTEM AT THE TEMPERATURE OF EMULSIFICATION. 